Acrylic block copolymers that have a structure formed by bonding of an acrylic acid ester polymer block and a methacrylic acid ester polymer block are conventionally known to be useful in various fields because of their flexibility and outstanding transparency and weather resistance. Such acrylic block copolymers are used in, for example, films and sheets in the optical field, and outdoor construction materials. Unfortunately, the acrylic block copolymers have limited fields of use because of the fact that the physical properties of the copolymer alone are insufficient as compared to styrene-based block copolymers.
Various methods have been proposed as approaches to improving the transparency and shaping workability of acrylic block copolymers. For example, Patent Literature 1 (WO 2010/055798) presents a resin composition obtained by mixing an acrylic block copolymer with a methacrylic resin and having excellent flexibility, transparency and shaping workability. Patent Literature 2 (WO 2012/057079) presents a resin composition obtained by mixing a methacrylic resin with an acrylic block copolymer and having excellent transparency, shaping properties and mechanical properties.
However, these techniques still have room for improvement in transparency and shaping workability, and there has been a demand for acrylic block copolymers that have excellent transparency, profile extrusion properties and surface smoothness of shaped articles and also have outstanding light guiding properties.